The visual sector of the reticular thalamic nucleus has come under some intense scrutiny over recent years, principally because of the key role that the nucleus plays in the processing of visual information. Despite this scrutiny, we know very little of how the connections between the reticular nucleus and the different areas of visual cortex and the different visual dorsal thalamic nuclei are organized. This study examines the patterns of reticular connections with the visual cortex and the dorsal thalamus in the rat, a species where the visual pathways have been well documented. Biotinylated dextran, an anterograde and retrograde tracer, was injected into different visual cortical areas [17; rostral 18a: presumed area AL: (anterolateral); caudal 18a: presumed area LM (lateromedial); rostral 18b: presumed area AM (anteromedial); caudal 18b: presumed area PM (posteromedial)] and into different visual dorsal thalamic nuclei (posterior thalamic, lateral geniculate nuclei), and the patterns of anterograde and retrograde labelling in the reticular nucleus were examined. From the cortical injections, we find that the visual sector of the reticular nucleus is divided into subsectors that each receive an input from a distinct visual cortical area, with little or no overlap. Further, the resulting pattern of cortical terminations in the reticular nucleus reflects largely the patterns of termination in the dorsal thalamus. That is, each cortical area projects to a largely distinct subsector of the reticular nucleus, as it does to a largely distinct dorsal thalamic nucleus. As with each of the visual cortical areas, each of the visual dorsal thalamic (lateral geniculate, lateral posterior, posterior thalamic) nuclei relate to a separate territory of the reticular nucleus, with little or no overlap. Each of these dorsal thalamic territories within the reticular nucleus receives inputs from one or more of the visual cortical areas. For instance, the region to the reticular nucleus that is labelled after an injection into the lateral geniculate nucleus encompasses the reticular regions which receive afferents from cortical areas 17, rostral 18b and caudal 18b. These results suggest that individual cortical areas may influence the activity of different dorsal thalamic nuclei through their reticular connections.
The organisation of the long descending corticofugal pathways is poorly understood. We have examined these pathways to determine the fibre relationships along the extent of their course through the internal capsule, cerebral peduncle, longitudinal pontine fasciculus, pyramid, pyramidal decussation, and dorsal column of the spinal cord. Different cytoarchitectonic regions (e.g., lateral agranular and granular) of the rat's neocortex were injected with the axonal tracer biotinylated dextran. In other experiments, each animal had different-coloured fluorescent tracers (Fluoro Ruby and dextran-fluorescein) injected into separate cortical areas. Our results show that in the anterior and posterior limbs of the internal capsule, axons arising from spatially separate sites in rat neocortex occupy distinct regions of the cross-sectional area of the pathway. More caudally, within the cerebral peduncle and the longitudinal pontine fasciculus, axons from more distant cortical areas remain largely separate, but those from adjacent cortical areas begin to overlap. By the medullary pyramid, the pyramidal decussation, and the dorsal column of the spinal cord, the representations of all the cortical regions injected overlap completely; in these structures, the axons arising from each cortical area are widely intermingled. Thus, along the rostral-to-caudal course of the corticofugal pathways, there is a change in the organisation of axons. At rostral levels, the order corresponds roughly to the spatial distribution of the cells of origin, but more caudally, this changes to an arrangement of axons that has no readily apparent order. A similar change has been observed along the course of the retinofugal pathway, where a decrease of spatial order in the fibre distribution has been associated with a reordering of axons according to their temporal sequence of outgrowth.
PurposeTo conduct a systematic literature review of the epidemiological and economic burden of surgical site infection (SSI) in Korea.MethodsA search of the EMBASE, Medline and KoreaMed databases for English and Korean language publications was conducted. Searches for epidemiological and economic studies were conducted separately and limited to 1995 to 2010 to ensure the pertinence of the data.ResultsTwenty-six studies were included. The overall incidence of SSI in Korea was 2.0 to 9.7%. The National Nosocomial Infections Surveillance risk index was positively correlated with the risk of developing an SSI. Specific risk factors for SSI, identified through multivariate analyses included; diabetes, antibiotic prophylaxis and wound classification. SSIs were associated with increased hospitalisation cost, with each episode of SSI estimated to cost about an additional ₩2,000,000. A substantial portion of the increased cost was attributed to hospital room costs and the need for additional medication. Studies also found that post-operative stays for patients with SSIs were 5 to 20 days longer, while two studies reported that following cardiac surgery, patients with SSIs spent an additional 5 to 11 days in the intensive care unit, compared to patients without SSIs.ConclusionData from the included studies demonstrate that SSI represents a significant clinical and economic burden in Korea. Consequently, the identification of high-risk patient populations and the development of strategies aimed at reducing SSI may lead to cost-savings for the healthcare system.
During early development, the perireticular thalamic nucleus is very large (i.e. has many cells) and has a strong projection to the dorsal thalamus and to the cerebral neocortex. By adulthood, the nucleus has much reduced in size and only a few cells remain. It is not clear whether these perireticular cells that remain into adulthood maintain their connections with the dorsal thalamus and with the neocortex. This study examines this issue by injecting neuronal tracers into various nuclei of the dorsal thalamus (dorsal lateral geniculate nucleus, medial geniculate complex, ventroposteromedial nucleus, lateral posterior nucleus, posterior thalamic nucleus) and into different areas of the neocortex (somatosensory, visual, auditory). After injections of tracer into the individual nuclei of the rat and ferret dorsal thalamus, retrogradely-labelled perireticular cells are seen. In general, after each injection, the retrogradely-labelled perireticular cells lie immediately adjacent to a group of retrogradely-labelled reticular cells. For instance, after injections into the medial geniculate complex, perireticular cells adjacent to the auditory reticular sector are retrogradely-labelled, whilst after an injection into the dorsal lateral geniculate nucleus, retrogradely-labelled perireticular cells adjacent to the visual reticular sector are seen. By contrast, injections of tracer into various areas of the rat and ferret neocortex result in no retrogradely-labelled cells in the perireticular nucleus. Thus, unlike during perinatal development when perireticular cells project to both neocortex and dorsal thalamus, perireticular cells in the adult seem to project to the dorsal thalamus only: the perireticular projection to the neocortex appears to be entirely transient.
Based on the results of this meta-analysis, desvenlafaxine was shown to be non-inferior to venlafaxine in terms of efficacy, and has an advantage in terms of less nausea.
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